Development of a Robotic Ankle Assist Device

Development of a Robotic Ankle Assist Device to Improve Mobility in Individuals With Movement Disorders

Northern Arizona University, Gillette Children's Specialty Healthcare, Shirley Ryan AbilityLab, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)

The overall objectives of this work is to establish feasibility of a robotic ankle assist device (RAAD) to improve mobility in free-living settings and to establish the RAAD as an effective tool to provide increased dose and precision of targeted ankle therapy. The first specific aim is to complete a personal-use feasibility analysis of ankle mobility assistance. It is hypothesized the children will be able to safely walk faster and travel farther in the community when using the RAAD device vs. without the device. The second specific aim is to gather feedback to design and prototype a minimum viable product for use in clinical and community settings. The third specific aim is to quantify the potential for the RAAD system to increase the effectiveness of clinical gait therapy. Individuals with CP will complete three training sessions: RAAD assistance, RAAD resistance and standard of care. Muscle activity and step activity will be measured during each session. It is hypothesized that the RAAD assistance and resistance therapy will improve ankle plantar-flexor muscle activity and treatment session quality compared to traditional physical therapist-guided gait training. The fourth specific aim is to assess the benefits of repeated gait training with RAAD assistance and resistance. Individuals with CP will participate in a 4-week assistance or resistance intervention and mobility outcomes will be quantified pre and post intervention. It is hypothesized that both assistance and resistance training will improve mobility outcomes.

This study has four experiments. In experiment I, participants will be recruited to complete user-centric device testing. In experiment 2, participants will be recruited to complete a study to determine effectiveness of the device during clinical gait therapy. In experiment three, participants will be recruited to complete gait training with the RAAD under assistance.In experiment four, participants will be recruited to complete gait training with the RAAD under resistance either (1) always under therapist supervision, or (2) with one therapist-supervised and two parent- supervised sessions per week.

The RAAD (Robotic Ankle Assist Device) is an intelligent, powered ankle device designed to increase independence, mobility, and deliver gait training to children with movement disorders, such as CP

Number of steps with mean late stance (i.e. propulsive) ankle plantar flexor activity above pre-session baseline average activity of 5 heel raises

Similarity of muscle activity to the average unimpaired activity pattern calculated via cross-correlation coefficient

Qualitative therapist assessment of session quality, participant movement, and device usability via questionnaire

Qualitative therapist assessment of session quality, participant movement quality, and device usability via questionnaire

Participant questionnaire of exertion, ankle muscle soreness, device usability, comfort, and ease of don/doffing

Qualitative participant assessment of exertion, ankle muscle soreness, device usability, comfort, and ease of don/doffing via questionnaire

Positive ankle power, and distribution of positive joint power across the lower extremity measured in Watts

Inclusion Criteria: Diagnosis of cerebral palsy. Any sex, race, ethnicity or socioeconomic status. GMFCS level I, II, or II. Ability to walk for at least 6 minutes (assisted or unassisted). Age between 8-18 years. Height/weight/BMI between the 5th - 95th percentile of children with CP. Able to understand and follow simple directions. Able to complete 5 heel raises with minimal assistance (balance only). At least 20 degrees of passive ankle plantar flexion range of motion. Exclusion Criteria: Knee extension or ankle dorsiflexion contractures greater than 15 degrees. Health condition or diagnosis other than CP that would affect safe participation. Orthopedic surgery completed in the prior 12-months. Current enrollment in a conflicting research study.